[Value of zinc transporter 8 autoantibody in the diagnostic classification of acute-onset diabetics].

Objective To explore the application significance of zinc transporter 8 autoantibody (ZnT8A) in the diagnostic classification of acute-onset diabetics. Methods According to the status of glutamic acid decarboxylase antibody(GADA) and tyrosine phosphatase antibody( IA2-A), 453 acute-onset diabetics were divided into A + subgroup ( any antibody positive ) and A - subgroup ( both antibodies negative). A total of 555 type 2 diabetics and 405 healthy controls were recruited. The distribution and correlated factors of ZnT8A were analyzed in the acute-onset diabetic group and two subgroups( A + and A- ). The clinical characteristics were compared between the patients with ZnT8A positive alone and patients without any antibody. All these islet antibodies were measured by radioligand assay. Results The prevalence of ZnT8A in acute-onset diabetics was 24.3% and it was significantly higher than that in type 2 diabetics( 1.8% ) and healthy controls( 1.0% ) ( both P ＜0.01 ). The frequency of ZnT8A in A + subgroup was much higher than A - subgroup(29.7% vs 15.8%, P ＜ 0.01 ). The positive rates of ZnT8A were much higher in all the subgroups with age at onset of ＜30yr than those with ≥30yr(0 -9, 34.9%; 10 -19, 26.7%; 20 -29, 26.3% vs ≥30 yr, 18.3%; all P＜0.05); furthermore, the rates were also higher in BMI ＜21.0 kg/m2 and 21.0 -25.0 kg/m2 subgroups than in BMI ＞25.0 kg/m2 subgroup(25.5% and 25.9% vs 8.7%, both P ＜ 0.05 ). The ZnT8A level was only positively correlated with IA2-A titer( r =0.165, P=0.01), but not related to such factors as GADA titer, age at onset, duration, body mass index,HbAlc and CP levels( all P ＞0.05). As compared with Ab- patients, the patients with ZnT8A positive alone had much higher insulin injection dosage [( 35.5 ± 9.3 ) U/d vs ( 29.8 ± 14.7 ) U/d, P ＜ 0.05], and much lower systolic blood pressures [( 107 ± 15 ) mm Hg vs ( 113 ± 16 ) mm Hg, P ＜ 0.05] and diastolic blood pressures [(69 ± 12) mm Hg vs (73 ± 12) mm Hg, P ＜ 0.05]. Conclusion ZnT8A testing may be applied in the diagnostic classification of acute-onset diabetics, especially in those without an evidence of GADA and IA2-A since it helps to identify a clinical phenotype which is more similar to the classic type 1 diabetes. Key words: Diabetes mellitus,type 1;  Diagnosis;  ZnT8 autoantibody;  Acute-onset